package HOT100;

import java.util.Scanner;

/**
 * @author 是阿秋啊
 * @date 2022/09/23 16:10
 **/
public class hande1 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        boolean[] dp = new boolean[n + 1];
        int[] arr = new int[n + 1];
        for (int i = 1; i <= n; i++) {
            for (int j = i; j <= n; j = j + i) {
                arr[j]++;
            }
        }
        for (int i = 1; i < dp.length; i++) {
            dp[i] = arr[i] % 2 == 1;
        }
        int count = 0;
        for (boolean b : dp) {
            if (b) {
                count++;
            }
        }
        System.out.println(count);
    }
}